US20200217807A1 - Real time additive manufacturing process inspection - Google Patents
Real time additive manufacturing process inspection Download PDFInfo
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- US20200217807A1 US20200217807A1 US16/243,606 US201916243606A US2020217807A1 US 20200217807 A1 US20200217807 A1 US 20200217807A1 US 201916243606 A US201916243606 A US 201916243606A US 2020217807 A1 US2020217807 A1 US 2020217807A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
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- G—PHYSICS
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- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
- G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
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- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
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- B33Y50/00—Data acquisition or data processing for additive manufacturing
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- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
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- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/25—Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
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- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/22—Driving means
- B22F12/226—Driving means for rotary motion
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- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/30—Platforms or substrates
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Definitions
- the present disclosure generally relates to methods and systems for additive manufacturing and, more particularly, to methods and systems for real time inspection during additive manufacturing.
- Additive manufacturing also called three dimensional (3-D) printing, encompasses many methods to “print” three dimensional objects by depositing layer upon layer of material and fusing them together.
- the technology has progressed so that complex industrial end-use parts can now be fabricated.
- Additive manufacturing techniques include, among others, directed energy deposition, binder jetting, material extrusion, powder bed fusion, sheet lamination, material jetting, and vat photo polymerization.
- Directed energy deposition for example, precisely deposits a layer of material, such as a powdered metal layer.
- a laser or electron beam thermally fuses the powdered metal.
- additive manufacturing can be used to fabricate final end use parts, it has become an important alternative to machining, casting, and injection molding. It can be used for the production of metal, composite, and polymer components for the most demanding of applications. As with any manufacturing process, undesirable internal defects such as voids, cracks, and porosity may sometimes be introduced during fabrication. Detection of these defects, however, must wait for completion of the additive manufacturing process. Using nondestructive methods such as computer tomography or ultrasonic techniques, defects in a completed object fabricated by additive manufacturing can be detected.
- a method for detecting defects during additive manufacturing includes pausing additive manufacturing of an object within a build chamber at a time T 1 , wherein T 1 is subsequent to a time T 0 and prior to a time T F , wherein time T 0 is a start of additive manufacturing of the object being formed and time T F is a completion of additive manufacturing of the object being formed in the build chamber.
- the method further includes rotating the object in the build chamber and directing an x-ray pulse from an x-ray tube through a linear aperture towards the object being formed and being rotated inside of the build chamber.
- a linear x-ray detector array detects the x-ray pulse subsequent to the x-ray pulse's interaction with the object being formed and being rotated.
- the method further includes creating an x-ray image of the object being formed based on the detected x-ray pulse.
- the method for detecting defects during additive manufacturing can further include analyzing the x-ray image of the object being formed to determine a presence of a defect and stopping additive manufacturing of the object being formed, prior to time T F , based on the presence of the defect.
- the method for detecting defects during additive manufacturing can further include analyzing the x-ray image of the object being formed to determine that defect is not present and resuming additive manufacturing of the object being formed.
- the method for detecting defects during additive manufacturing can further include pausing additive manufacturing of an object within a build chamber at a time T 2 , wherein time T 2 is subsequent to time T 1 and prior to a time T F . Then, directing a second x-ray pulse, at time T 2 , towards the object being formed inside of the build chamber while rotating the object being formed.
- the method can further include detecting the second x-ray pulse, by the linear x-ray detector array, subsequent to the second x-ray pulse's interaction with the object being formed and creating a second x-ray image of the object being formed based on the detected second x-ray pulse.
- the method for detecting defects during additive manufacturing can further include pausing additive manufacturing of an object within a build chamber at a time T N , wherein time T N is subsequent to time T 2 and prior to a time T F , wherein N is an integer greater than 2; directing an N th x-ray pulse, at time T N , towards the object being formed inside of the build chamber while rotating the object being formed.
- the method can also include detecting the N th x-ray pulse, by the linear x-ray detector array, subsequent to the N th x-ray pulse's interaction with the object being formed and creating another x-ray image of the object being formed based on the detected N th x-ray pulse.
- the method includes pausing additive manufacturing of an object within a build chamber at a time T 1 , wherein T 1 is subsequent to a time T 0 and prior to a time T F , wherein time T 0 is a start of additive manufacturing of the object being formed and time T F is a completion of additive manufacturing of the object being formed in the build chamber.
- the object in the build chamber can be moved linearly in a direction perpendicular to an linear aperture and a linear x-ray detector, wherein the linear aperture and the linear x-ray detector are disposed outside of the build chamber.
- An x-ray pulse can be directed from an x-ray tube through the linear aperture towards the object being formed and moved inside of the build chamber to scan the object being formed.
- the x-ray pulse can be detected by a linear x-ray detector array, subsequent to the x-ray pulse scanning the object being formed. And an x-ray image of the object being formed can be created based on the detected x-ray pulse.
- an inspection system for additive manufacturing includes an actuator, wherein the actuator is arranged in a build chamber to support an object being formed by additive manufacturing; an x-ray tube disposed adjacent to a side of the turntable and outside of the build chamber; a linear aperture disposed between the x-ray tube and the build chamber; and a linear x-ray detector array disposed at an opposite side of the turntable from the x-ray tube and outside of the build chamber.
- the inspection system for additive manufacturing further includes a computer and an image analyzer comprising a memory system having one or more non-transitory computer readable media storing instructions that, when executed, causes the image analyzer to form an x-ray image from signals received from the linear x-ray detector array.
- the inspection system includes an x-ray tube disposed adjacent to a side and outside of a build chamber; an aperture disposed between the x-ray tube and the build chamber, wherein the x-ray tube and the aperture are attached to an x-ray tube actuator arranged to move the x-ray tube and the aperture relative to the build chamber; and a linear x-ray detector array disposed at an opposite side of the build chamber from the x-ray tube and outside of the build chamber, wherein the linear x-ray detector array is attached to a linear x-ray detector array actuator arranged to move the linear x-ray detector array relative to the build chamber.
- the inspection system for additive manufacturing further includes a computer and an image analyzer comprising a memory system having one or more non-transitory computer readable media storing instructions that, when executed, causes the image analyzer to form an x-ray image from signals received from the linear x-ray detector array.
- the method includes pausing additive manufacturing of an object within a build chamber at a time T 1 , wherein T 1 is subsequent to a time T 0 and prior to a time T F , wherein time T 0 is a start of additive manufacturing of the object being formed and time T F is a completion of additive manufacturing of the object being formed in the build chamber.
- the method further includes moving an x-ray tube and a linear x-ray detector array in linear and synchronized manner, wherein the x-ray tube and the linear x-ray detector array are disposed outside of the build chamber.
- An x-ray pulse can then be directed from the x-ray tube through a linear aperture towards the object being formed to scan the object being formed.
- the x-ray pulse can be detected by the linear x-ray detector array, subsequent to the x-ray pulse scanning the object being formed and an x-ray image of the object being formed can be created based on the x-ray pulse that was detected.
- the method includes pausing additive manufacturing of an object within a build chamber at a time T 1 , wherein T 1 is subsequent to a time T 0 and prior to a time T F , wherein time T 0 is a start of additive manufacturing of the object being formed and time T F is a completion of additive manufacturing of the object being formed in the build chamber.
- the method further includes rotating one of an x-ray tube and a linear x-ray detector array and moving in an arc the other of the x-ray tube and the linear x-ray detector array to maintain a distance between the linear x-ray detector array and the x-ray tube, wherein the x-ray tube and the linear x-ray detector array are disposed outside of the build chamber.
- An x-ray pulse can be directed from the x-ray tube through a linear aperture towards the object being formed to scan the object being formed.
- the x-ray pulse can be detected by the linear x-ray detector array, subsequent to the x-ray pulse scanning the object being formed and an x-ray image of the object being formed can be created based on the x-ray pulse that was detected.
- FIG. 1 schematically depicts a system for real time inspection of an object during additive manufacturing of the object according to the present disclosure
- FIG. 2 illustrates operations performed in a method for real time inspection of an object during additive manufacturing of the object according to the present disclosure
- FIG. 3 schematically depicts a system for real time inspection of a metal object during additive manufacturing of the metal object by directed energy deposition according to the present disclosure
- FIG. 4 schematically depicts another system for real time inspection of a metal object during additive manufacturing of the metal object by directed energy deposition according to the present disclosure
- FIG. 5 illustrates operations performed in a method for real time inspection of an object during additive manufacturing of the object according to the present disclosure.
- the disclosed x-ray based system and method can nondestructively detect defects within an object in real time, as the object is being fabricated, by additive manufacturing. Inspection can be accomplished without needing to modify or otherwise disrupt the environment inside the build chamber, for example a vacuum, inert gas, or elevated temperature environment.
- the disclosed system and method is not limited by the type and size of the build chamber or the type of additive manufacturing technique being used, Moreover, the disclosed system and method is not affected by smoke, particles, or liquid that may be present in the build chamber. Real time detection of defects during additive manufacturing can save time, material, and money by stopping or correcting the process immediately upon detection of a defect instead of waiting until completion of the additive manufacturing process.
- FIG. 1 shows an inspection system 100 that can be used during additive manufacturing, according to the present disclosure.
- Inspection system 100 can include an x-ray tube 110 , an aperture 120 , an actuator 130 , a linear x-ray detector array 140 , a computer 150 , a controller 154 , and an image analyzer 156 .
- X-ray tube 110 is positioned adjacent to and outside of a build chamber 160 .
- X-ray tube 110 can be, for example, an x-ray tube used for baggage screening in airports.
- the type of x-ray tube 110 can depend on the objected being additively manufactured, its composition, and the type of additive manufacturing technique being used.
- x-ray tube 110 can be glass or ceramic and have power ranging from about 100 to about 4000 watts and voltages ranging from about 30 to about 450 kV. Suitable x-ray tubes are manufactured by, for example, Phillips, Varian, and General Electric.
- X-ray tube 110 further includes a cooling system, for example, circulating water or closed cycle cooling to control the temperature of the x-ray tube.
- Aperture 120 is positioned between build chamber 160 and x-ray tube 110 to provide a collimated fan beam directed to an object being fabricated inside of build chamber 160 .
- Aperture 120 can be formed of any material that blocks x-rays, including but not limited to lead, steel, and tungsten.
- Aperture 120 is controlled by controller 154 to provide pulses of about 1 second to about 60 seconds directed at an object being fabricated inside of build chamber 160 .
- Aperture 120 can be, for example, a linear aperture formed of lead or steel.
- Actuator 130 is disposed within a build chamber 160 and either directly or indirectly supports the object being fabricated.
- Actuator 130 can be a rotary actuator, such as a turntable, that rotates under the control of controller 154 , at a speed from about one revolution per second to about one revolution per 10 minutes. This allows the x-ray pulse to interact with the entire volume of the object being fabricated.
- Actuator 130 can be a motorized turntable with an optical encoder that provides accurate positioning so the x-ray image can correlate to the positon of the object being formed inside of build chamber 160 .
- actuator 130 can be a linear actuator that supports and moves the object being fabricated in a linear direction, for example, into and out of the page, as shown in FIG. 1 .
- the linear actuator can move under the control of controller 154 at a speed from about 100 cm/sec to about 1 cm/minute to allow the x-ray pulse to interact with the entire volume of the object being fabricated.
- the linear actuator can move the object being fabricated so that the entire volume of the object is scanned by the x-ray pulse.
- Linear x-ray detector array 140 is positioned outside of build chamber 160 to detect the x-ray pulse after it passes through and interacts with an object being fabricated on actuator 130 .
- Linear x-ray detector array 140 can be, for example, a one-dimensional x-ray detector consisting of at least one row of x-ray sensitive detectors. Data from linear x-ray detector array 140 is digitized and sent to a computer 150 and analyzed by image analyzer 156 . By moving either the object being fabricated or the detector in a direction perpendicular to the length of linear x-ray detector array 140 , a two dimensional image of the object can be created. As shown in FIG.
- actuator 130 is a turntable that rotates the object being fabricated in a direction perpendicular to the length dimension of linear x-ray detector array 140 .
- Linear x-ray detector array 140 can be, for example, a silicon (Si) or complementary metal-oxide-semiconductor (CMOS) based detector with scintillating materials on top. Scintillating materials can be, for example, CsI:Na, Gd 2 O 2 S, or CaWO 4 , to convert x-rays to visible light.
- actuator 130 is a linear actuator
- the linear actuator moves the object being fabricated in a direction into and out of the page, so that the entire volume of the object being fabricated is scanned by the linear x-ray pulse and the x-rays are detected by linear x-ray detector array 140 subsequent to the x-rays interacting with the object being fabricated.
- Inspection system 100 further includes computer 150 , controller 154 , and image analyzer 156 .
- Computer 150 is operably coupled to x-ray tube 110 , aperture 120 , actuator 130 , and linear x-ray detector array 140 .
- Computer 150 includes processors and a memory system including one or more non-transitory computer readable media storing instructions that, when executed, synchronizes actions by x-ray tube 110 , aperture 120 , actuator 130 , and linear x-ray detector array 140 .
- computer 150 through controller 154 , synchronizes via processors and software, the rotation or linear movement of actuator 130 with the exposure time of linear x-ray detector array 140 to maintain regular image geometry.
- Controller 154 further controls aperture 120 to provide an x-ray pulse having the desired pulse width and controls operation of x-ray tube 110 to provide the desired energy.
- Image analyzer 156 can include, for example, software to create x-ray images from data received from linear x-ray detector array 140 .
- Image analyzer 156 can further include software to identify defects in the x-ray images, for example, pattern recognition software that compares the x-ray images to defect-free x-ray images. For example, by comparing an x-ray image of the object being formed to an x-ray image of a defect free object, the pattern recognition software can identify anomalies or defects, such as unplanned voids or inconsistencies, in the x-ray image of the object being formed.
- other components may be included in inspection system 100 .
- other software/devices can be used to capture, manipulate, analyze, and display the x-ray images or to control other devices such as the hardware related to the additive manufacturing system including build material deposition and fusing.
- Build chamber 160 shown in cross section in FIG. 1 , is generally part of an additive manufacturing system. It can take on many forms depending on the type of additive manufacturing technique, but is generally an enclosure in which additive manufacturing occurs. Build chamber 160 can range from a simple glass or polymer enclosure to a complex enclosure in which temperature and/or pressure and/or atmospheric content is tightly controlled. An advantage of the disclosed system and method, is that it is independent of the type of build chamber because x-rays can penetrate most materials.
- FIG. 2 shows a method 200 for nondestructive inspection of an object during fabrication by additive manufacturing according to the present disclosure.
- Method 200 is described herein with respect to a metal powder fed additive manufacturing system 301 shown in FIG. 3 .
- Metal powder fed additive manufacturing systems are also known as laser cladding, directed energy deposition, and laser metal deposition systems.
- reference to metal powder fed system 301 is for descriptive purposes and that the disclosed system and method can be used in other types of additive manufacturing systems and is not limited to additive manufacturing of metal objects.
- FIG. 3 shows a metal powder fed additive manufacturing system 301 including a build chamber 360 , a metal powder feeder 380 , and a laser beam 382 .
- metal powder feeder 380 deposits metal powder while laser beam 382 fuses the metal powder at the surface of an object 399 being formed layer by layer.
- Metal powder feeder can include, for example, a nozzle mounted on a 4 or 5 axis arm.
- the type of laser can depend on the powdered metal being deposited. Because directed energy deposition systems often require an inert atmosphere, access to build chamber 360 during fabrication by additive manufacturing is limited.
- Real time, nondestructive inspection of object 399 during additive manufacturing by metal powder fed system 301 can be accomplished by incorporating an x-ray tube 310 , a linear aperture 320 , an actuator 330 , a linear x-ray detector array 340 , a computer 350 , a controller 354 , and image analyzer 156 .
- Additive manufacturing systems for example metal powder fed system 301 used for descriptive purposes herein, may already include a computer and controller that can be utilized.
- software or hardware components may need to be added to the existing computer and controller of the additive manufacturing system to incorporate control of x-ray tube 310 , linear aperture 320 , actuator 330 , and/or linear x-ray detector array 340 .
- another computer and controller separate from the computer and controller of the additive manufacturing system, can be used.
- metal powder feeder 380 pauses depositing metal powder and fusing by laser beam 382 , for example by turning off the laser that provides laser beam 382 or redirecting laser beam 382 away from object 399 .
- Build chamber 360 does not need to be opened, the environment inside does not need to be changed, and object 399 does not need to be removed from the build chamber. This can minimize the amount of time the additive manufacturing process is paused. Pausing the additive manufacturing process can be simply stopping deposition and fusing of the build material for a brief period of time, for example, after formation of one layer and prior to formation of the next layer.
- the additive manufacturing process can be determined based on a number of factors including, but not limited to, the size and complexity of the object being fabricated, the number of inspections desired, and the type of additive manufacturing being used. For example, pausing at 210 can occur subsequent to fabrication of a complex portion of object 399 but prior to completion of fabrication of object 399 .
- actuator 330 such as a turntable, rotates object 399 in a direction perpendicular to a length dimension of linear x-ray detector array 340 .
- Controller 354 can control the speed of rotation, as well as the start and stop of the rotation. Rotation of actuator 330 can begin either before, during, or after x-rays interact with object 399 .
- the speed of rotation can depend on the size of object 399 and/or the x-ray pulse width and can range from about one revolution per second to about one revolution per 10 minutes.
- actuator 330 moves object 399 in a linear direction perpendicular and between linear x-ray detector array 340 and x-ray tube 310 .
- Controller 354 can control the linear speed, as well as the start and stop of the linear motion. Movement of object being formed 399 by actuator 330 can begin either before, during, or after x-rays interact with object 399 .
- the speed of movement can depend on the size of object 399 and/or the x-ray pulse width and can range from about 100 cm/sec to about 1 cm/min.
- an x-ray pulse is directed towards object 399 .
- the x-ray pulse can occur at a time T 1 .
- Time T 1 is subsequent to a time T 0 and prior to a time T F , wherein time T 0 is a start of additive manufacturing of object 399 and time T F is a completion of additive manufacturing of object 399 within build chamber 360 .
- x-rays are generated by x-ray tube 310 .
- Linear aperture 320 under the control of controller 354 , provides a collimated fan shaped x-ray pulse that interacts with object 399 as it is being rotated by actuator 330 .
- the x-ray pulse can have a pulse duration of about 1 second to about 60 seconds and an energy of about 50 to about 250 keV. Current can range from about 1 to about 20 mA.
- the x-ray pulse duration allows x-rays to interact with the object being formed as the object is being rotated or moved linearly. Factors influencing pulse width include the size of the object being formed and the speed of rotation or linear movement. Typically, a larger object or slower rotation or movement will require a longer pulse width.
- Energy and current of the x-ray pulse are determined by the size and composition of the object being formed so that the x-rays can penetrate the object being formed and the build chamber before being detected.
- Linear aperture 320 provides a collimated fan beam having a narrow width. The collimated fan beam can further have a length, for example, long enough to inspect object 399 at its largest dimensions when fabrication is completed.
- the path and pulse shape of the x-ray pulse are depicted in FIG. 3 as an x-ray pulse 311
- x-ray pulse 311 is detected by linear x-ray detector array 340 .
- the speed of actuator 330 moving object 399 and the pulse width of x-ray pulse 311 allow linear x-ray detector array 340 to detect the x-ray subsequent to interaction with an entire volume of object 399 .
- actuator 330 is a turntable
- the turntable can rotate object 399 one half turn to allow x-ray pulse 311 to interact with object 399 .
- one half turn refers to object 399 rotating one half of one full rotation with respect to turntable or object 399 .
- actuator 330 can rotate object 399 one full turn or more.
- the data collected by linear x-ray detector array 340 is sent to computer 350 .
- controller 354 under the direction of computer 350 can stop rotation of actuator 330 .
- Controller 354 controls actuator 330 , whether a turntable or linear actuator, so that object 399 is at the same position after rotation or linear movement. In other words, controller 354 returns object 399 to the same position relative to metal powder feeder 380 and laser beam 382 so that additive manufacturing can continue.
- an x-ray image is created based on the x-rays detected by linear x-ray detector array 340 .
- an x-ray image representing a volume of object 399 can be created.
- the x-ray image can be, for example, a digital image created by image analyzer 356 .
- the x-ray image is analyzed at 260 of method 200 by image analyzer 356 .
- image analyzer 356 can use pattern recognition to compare the x-ray image of object 399 to control image, for example, an x-ray image of an object with no defects. Defects of about 1 mm and larger can be detected.
- additive manufacturing can be stopped at 270 . Stopping the additive manufacturing process at this point, prior to completion of fabrication, can save time, material, and cost.
- the additive manufacturing can resume fabrication of object 399 , as shown at 280 of method 200 .
- resuming additive manufacturing means that actuator 330 , for example, the turntable, under the direction of controller 354 , has stopped rotating and metal powder feeder 380 begins to deposit metal powder while laser beam 382 fuses the metal powder at the surface of object 399 .
- fabrication can resume at any time after detection of the x-rays by linear x-ray detector array 340 . In other words, additive manufacturing can resume before completion of the analysis of whether a defect exists.
- fabrication of object 399 can continue to completion. If another inspection is desired, for example at a time T 2 , where T 2 is subsequent to time T 1 and prior to time T F , fabrication of object 399 can again be paused and can return to 210 of method 200 as shown in FIG. 2 . Operations 210 thru 260 of method 200 can then be repeated as desired or until fabrication is complete. In other words, between time T 0 and T F and subsequent to T 2 , x-rays can be directed at object 399 and x-ray images created as many times as desired.
- x-rays can be directed at object 399 and x-ray images created at a time T N where time T N is an integer greater than 2.
- time T N is an integer greater than 2.
- the additive manufacturing process can be paused and the object inspected, for example, 10 times so that 10 x-ray images are formed at times T 1 thru T 10 , respectively.
- each of the pauses occurs can also be determined as desired.
- T 1 (or T N ) can be set to occur after fabrication of a particularly complex portion of object 399 .
- the timing of multiple pauses of the additive manufacturing process and inspection of the object does not have to be evenly spaced and can occur any time during fabrication.
- method 200 can be advantageously automated. For example, resuming or stopping the additive manufacturing process is accomplished without an operator by using, for example, computer 350 , controller 354 , and image analyzer 356 . Determining whether a defect exists using image processing and pattern recognition software can increase consistency of results. If desired, however, a trained technician can be used to perform the inspection and/or determination of whether a defect exists.
- FIGS. 4 and 5 show another inspection system and method that can be used for real time inspection during additive manufacturing, according to the present disclosure.
- the object being formed is stationary while one or both of the x-ray tube and the linear x-ray detector array is moved.
- the inspection system and method are described with reference to metal powder fed system 401 .
- Metal powder fed system 401 includes a build chamber 460 , a fabrication stand 430 , a metal powder feeder 480 , and a laser beam 482 .
- Metal powder feeder 480 can include, for example, a nozzle mounted on a 4 or 5 axis arm. The type of laser can depend on the powdered metal being deposited.
- An x-ray tube 410 , an aperture 420 , a linear x-ray detector array 440 , a computer 450 , a controller 454 , and an image analyzer 456 can be incorporated into metal powder fed system 401 .
- an x-ray tube actuator 405 can be used to move one or both of x-ray tube 410 and aperture 420 .
- linear x-ray detector array aperture 406 can be used to move linear x-ray detector array 440 .
- fabrication stand 430 remains stationary and can support an object being fabricated 499 .
- x-ray tube 410 and linear x-ray detector array 440 can both move linearly.
- one of x-ray tube 410 and linear x-ray detector array 440 can rotate while the other moves in an arc to maintain a same relative distance between the two. Moving the x-ray tube and the linear x-ray detector array relative to the stationary fabrication stand can reduce disruption of the additive manufacturing process because the change in relative position of object being fabricated 499 to the positions of metal powder feeder 480 and laser beam 482 can be minimized.
- actuators can be used.
- x-ray tube 410 can be attached to x-ray tube actuator 405 that moves both x-ray tube 410 and aperture 420 in a linear manner, for example into and out of the page depicted in FIG. 4 .
- linear x-ray detector array 440 can be attached to linear x-ray detector array actuator 406 that also moves linearly, for example, into and out of the page of FIG. 4 and in a synchronized manner with the movement of x-ray tube 410 and aperture 420 .
- linear x-ray detector array actuator 406 can rotate linear x-ray detector array 440 to match the movement of x-ray tube actuator 405 that moves both x-ray tube 410 and aperture 420 in arc.
- linear x-ray detector array actuator 406 can move linear x-ray detector array 440 in an arc to match the rotation of x-ray tube actuator 405 that rotates both x-ray tube 410 and aperture 420 .
- a method 500 for real time inspection during additive manufacturing is similar to the method 200 shown in FIG. 2 .
- controller 454 can control the speed, as well as the start and stop of the motion of both x-ray tube actuator 405 and linear x-ray detector array actuator 406 .
- Controller 454 also synchronizes their movement to scan the entire volume of object being fabricated 499 .
- the speed of movement of one or both actuators can depend on the size of object being fabricated 499 and/or the x-ray pulse width and can range from about 100 cm/sec to about 1 cm/min.
- Method 500 is described herein with respect to a metal powder fed additive manufacturing system 401 shown in FIG. 4 .
- metal powder fed system 401 is for descriptive purposes and that the disclosed system and method can be used in other types of additive manufacturing systems and is not limited to additive manufacturing of metal objects.
- deposition and fusing of material to form an object by additive manufacturing is paused, for example, by stopping deposition of metal powder and turning off the laser that provides laser beam 482 or redirecting laser beam 482 away from object 499 .
- Build chamber 460 does not need to be opened, the environment inside does not need to be changed, and object 499 does not need to be removed from the build chamber. This can minimize the amount of time the additive manufacturing process is paused.
- x-ray tube actuator 405 and linear x-ray detector array actuator 406 can move x-ray tube 410 and linear x-ray detector array 440 , respectively, in a linear manner, for example, into and out of the page of FIG. 4 .
- Controller 454 synchronizes the linear motion so the object being fabricated 499 is scanned by x-ray pulse 411 and subsequently detected by linear x-ray detector array 440 .
- X-ray tube actuator 405 also moves aperture 420 in a synchronized manner with x-ray tube 410 and linear x-ray detector array 440 .
- x-ray tube actuator 405 and linear x-ray detector array actuator 406 can rotate one of x-ray tube 410 and linear x-ray detector array 440 , and the other of x-ray tube actuator 405 and linear x-ray detector array actuator 406 can move in an arc. This can maintain the distance between x-ray tube 410 and linear x-ray detector array 440 .
- X-ray tube actuator 405 also moves aperture 420 in a synchronized manner with x-ray tube 410 and linear x-ray detector array 440 .
- Controller 454 synchronizes the motion of aperture 420 , x-ray tube 410 , and linear x-ray detector array 440 so the object being fabricated 499 is scanned by x-ray pulse 411 and subsequently detected by linear x-ray detector array 440 .
- an x-ray pulse is directed towards object 499 at the same time as x-ray tube actuator 405 moves x-ray tube 410 and aperture 420 , and linear x-ray detector array actuator 406 moves linear x-ray detector array 440 .
- object 499 is scanned by the x-ray pulse as one or both of the x-ray tube and linear x-ray detector array are moved linearly, in an arc or rotated.
- the x-ray pulse can occur at a time T 1 .
- Time T 1 is subsequent to a time T 0 and prior to a time T F , wherein time T 0 is a start of additive manufacturing of object 499 and time T F is a completion of additive manufacturing of object 499 within build chamber 460 .
- x-rays are generated by x-ray tube 410 .
- Linear aperture 420 under the control of controller 454 , provides a collimated fan shaped x-ray pulse that interacts with object 499 .
- the x-ray pulse can have a pulse duration of about 1 second to about 60 seconds and an energy of about 50 to about 250 keV. Current can range from about 1 to about 20 mA.
- the x-ray pulse duration allows x-rays to interact with the object being formed as the x-ray tube and/or linear x-ray detector array is being moved linearly or in an arc.
- the collimated fan beam can further have a length, for example, long enough to inspect object 499 at its largest dimensions when fabrication is completed.
- x-ray pulse 411 is detected by linear x-ray detector array 540 .
- the speed of actuators 405 and 406 moving object 499 and the pulse width of x-ray pulse 411 allow linear x-ray detector array 440 to detect the x-rays subsequent to interaction with an entire volume of object 499 . In other words, scanning of the entire volume of object 399 can be accomplished by controlling the pulse width and speed of actuators 405 and 406 .
- the data collected by linear x-ray detector array 440 is sent to computer 450 . At this point, controller 454 under the direction of computer 450 can stop motion of actuators 405 and 406 .
- an x-ray image is created based on the x-rays detected by linear x-ray detector array 440 .
- an x-ray image representing a volume of object 499 can be created.
- the x-ray image can be, for example, a digital image created by image analyzer 456 .
- the x-ray image is analyzed at 560 of method 500 by image analyzer 456 .
- image analyzer 456 can use pattern recognition to compare the x-ray image of object 499 to control image, for example, an x-ray image of an object with no defects. Defects of about 1 mm and larger can be detected.
- additive manufacturing can be stopped at 570 . Stopping the additive manufacturing process at this point, prior to completion of fabrication, can save time, material, and cost.
- the additive manufacturing can resume fabrication of object 499 , as shown at 580 of method 500 .
- resuming additive manufacturing means that metal powder feeder 480 begins to deposit metal powder while laser beam 482 fuses the metal powder at the surface of object 499 .
- fabrication can resume at any time after detection of the x-rays by linear x-ray detector array 440 . In other words, additive manufacturing can resume before completion of the analysis of whether a defect exists.
- fabrication of object 499 can continue to completion. If another inspection is desired, for example at a time T 2 , where T 2 is subsequent to time T 1 and prior to time T F , fabrication of object 499 can again be paused and can return to 510 of method 500 as shown in FIG. 5 . Operations 510 thru 560 of method 500 can then be repeated as desired or until fabrication is complete. In other words, between time T 0 and T F and subsequent to T 2 , x-rays can be directed at object 499 and x-ray images created as many times as desired.
- x-rays can be directed at object 499 and x-ray images created at a time T N where time T N is an integer greater than 2.
- time T N is an integer greater than 2.
- the additive manufacturing process can be paused and the object inspected, for example, 10 times so that 10 x-ray images are formed at times T 1 thru T 10 , respectively.
- each of the pauses occurs can also be determined as desired.
- T 1 (or T N ) can be set to occur after fabrication of a particularly complex portion of object 499 .
- the timing of multiple pauses of the additive manufacturing process and inspection of the object does not have to be evenly spaced and can occur any time during fabrication.
- method 500 can be advantageously automated. For example, resuming or stopping the additive manufacturing process is accomplished without an operator by using, for example, computer 450 , controller 454 , and image analyzer 456 . Determining whether a defect exists using image processing and pattern recognition software can increase consistency of results. If desired, however, a trained technician can be used to perform the inspection and/or determination of whether a defect exists.
- the term “at least one of” is used to mean one or more of the listed items can be selected.
- the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein.
- the term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated implementation.
- “exemplary” indicates the description is used as an example, rather than implying that it is an ideal.
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Abstract
Description
- The present disclosure generally relates to methods and systems for additive manufacturing and, more particularly, to methods and systems for real time inspection during additive manufacturing.
- Additive manufacturing, also called three dimensional (3-D) printing, encompasses many methods to “print” three dimensional objects by depositing layer upon layer of material and fusing them together. The technology has progressed so that complex industrial end-use parts can now be fabricated. Additive manufacturing techniques include, among others, directed energy deposition, binder jetting, material extrusion, powder bed fusion, sheet lamination, material jetting, and vat photo polymerization. Directed energy deposition, for example, precisely deposits a layer of material, such as a powdered metal layer. During deposition, a laser or electron beam thermally fuses the powdered metal. By continuing to precisely deposit powdered metal layers and fusing them together, a desired 3-D object or component can be fabricated within a build chamber.
- Because additive manufacturing can be used to fabricate final end use parts, it has become an important alternative to machining, casting, and injection molding. It can be used for the production of metal, composite, and polymer components for the most demanding of applications. As with any manufacturing process, undesirable internal defects such as voids, cracks, and porosity may sometimes be introduced during fabrication. Detection of these defects, however, must wait for completion of the additive manufacturing process. Using nondestructive methods such as computer tomography or ultrasonic techniques, defects in a completed object fabricated by additive manufacturing can be detected.
- According to the present teachings, a method for detecting defects during additive manufacturing is provided. The method includes pausing additive manufacturing of an object within a build chamber at a time T1, wherein T1 is subsequent to a time T0 and prior to a time TF, wherein time T0 is a start of additive manufacturing of the object being formed and time TF is a completion of additive manufacturing of the object being formed in the build chamber. The method further includes rotating the object in the build chamber and directing an x-ray pulse from an x-ray tube through a linear aperture towards the object being formed and being rotated inside of the build chamber. A linear x-ray detector array then detects the x-ray pulse subsequent to the x-ray pulse's interaction with the object being formed and being rotated. The method further includes creating an x-ray image of the object being formed based on the detected x-ray pulse.
- According to the present teachings, the method for detecting defects during additive manufacturing can further include analyzing the x-ray image of the object being formed to determine a presence of a defect and stopping additive manufacturing of the object being formed, prior to time TF, based on the presence of the defect.
- According to the present teachings, the method for detecting defects during additive manufacturing can further include analyzing the x-ray image of the object being formed to determine that defect is not present and resuming additive manufacturing of the object being formed.
- According to the present teachings, the method for detecting defects during additive manufacturing can further include pausing additive manufacturing of an object within a build chamber at a time T2, wherein time T2 is subsequent to time T1 and prior to a time TF. Then, directing a second x-ray pulse, at time T2, towards the object being formed inside of the build chamber while rotating the object being formed. The method can further include detecting the second x-ray pulse, by the linear x-ray detector array, subsequent to the second x-ray pulse's interaction with the object being formed and creating a second x-ray image of the object being formed based on the detected second x-ray pulse.
- According to the present teachings, the method for detecting defects during additive manufacturing can further include pausing additive manufacturing of an object within a build chamber at a time TN, wherein time TN is subsequent to time T2 and prior to a time TF, wherein N is an integer greater than 2; directing an Nth x-ray pulse, at time TN, towards the object being formed inside of the build chamber while rotating the object being formed. The method can also include detecting the Nth x-ray pulse, by the linear x-ray detector array, subsequent to the Nth x-ray pulse's interaction with the object being formed and creating another x-ray image of the object being formed based on the detected Nth x-ray pulse.
- According to the present teachings, another method for detecting defects during additive manufacturing is provided. The method includes pausing additive manufacturing of an object within a build chamber at a time T1, wherein T1 is subsequent to a time T0 and prior to a time TF, wherein time T0 is a start of additive manufacturing of the object being formed and time TF is a completion of additive manufacturing of the object being formed in the build chamber. The object in the build chamber can be moved linearly in a direction perpendicular to an linear aperture and a linear x-ray detector, wherein the linear aperture and the linear x-ray detector are disposed outside of the build chamber. An x-ray pulse can be directed from an x-ray tube through the linear aperture towards the object being formed and moved inside of the build chamber to scan the object being formed. The x-ray pulse can be detected by a linear x-ray detector array, subsequent to the x-ray pulse scanning the object being formed. And an x-ray image of the object being formed can be created based on the detected x-ray pulse.
- According to the present teachings, an inspection system for additive manufacturing is provided. The inspection system includes an actuator, wherein the actuator is arranged in a build chamber to support an object being formed by additive manufacturing; an x-ray tube disposed adjacent to a side of the turntable and outside of the build chamber; a linear aperture disposed between the x-ray tube and the build chamber; and a linear x-ray detector array disposed at an opposite side of the turntable from the x-ray tube and outside of the build chamber. The inspection system for additive manufacturing further includes a computer and an image analyzer comprising a memory system having one or more non-transitory computer readable media storing instructions that, when executed, causes the image analyzer to form an x-ray image from signals received from the linear x-ray detector array.
- According to the present teachings, another inspection system for additive manufacturing is provided. The inspection system includes an x-ray tube disposed adjacent to a side and outside of a build chamber; an aperture disposed between the x-ray tube and the build chamber, wherein the x-ray tube and the aperture are attached to an x-ray tube actuator arranged to move the x-ray tube and the aperture relative to the build chamber; and a linear x-ray detector array disposed at an opposite side of the build chamber from the x-ray tube and outside of the build chamber, wherein the linear x-ray detector array is attached to a linear x-ray detector array actuator arranged to move the linear x-ray detector array relative to the build chamber. The inspection system for additive manufacturing further includes a computer and an image analyzer comprising a memory system having one or more non-transitory computer readable media storing instructions that, when executed, causes the image analyzer to form an x-ray image from signals received from the linear x-ray detector array.
- According to the present teachings, another method for detecting defects during additive manufacturing is provided. The method includes pausing additive manufacturing of an object within a build chamber at a time T1, wherein T1 is subsequent to a time T0 and prior to a time TF, wherein time T0 is a start of additive manufacturing of the object being formed and time TF is a completion of additive manufacturing of the object being formed in the build chamber. The method further includes moving an x-ray tube and a linear x-ray detector array in linear and synchronized manner, wherein the x-ray tube and the linear x-ray detector array are disposed outside of the build chamber. An x-ray pulse can then be directed from the x-ray tube through a linear aperture towards the object being formed to scan the object being formed. The x-ray pulse can be detected by the linear x-ray detector array, subsequent to the x-ray pulse scanning the object being formed and an x-ray image of the object being formed can be created based on the x-ray pulse that was detected.
- According to the present teachings, another method for detecting defects during additive manufacturing is provided. The method includes pausing additive manufacturing of an object within a build chamber at a time T1, wherein T1 is subsequent to a time T0 and prior to a time TF, wherein time T0 is a start of additive manufacturing of the object being formed and time TF is a completion of additive manufacturing of the object being formed in the build chamber. The method further includes rotating one of an x-ray tube and a linear x-ray detector array and moving in an arc the other of the x-ray tube and the linear x-ray detector array to maintain a distance between the linear x-ray detector array and the x-ray tube, wherein the x-ray tube and the linear x-ray detector array are disposed outside of the build chamber. An x-ray pulse can be directed from the x-ray tube through a linear aperture towards the object being formed to scan the object being formed. The x-ray pulse can be detected by the linear x-ray detector array, subsequent to the x-ray pulse scanning the object being formed and an x-ray image of the object being formed can be created based on the x-ray pulse that was detected.
- It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.
- The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the present disclosure and together with the description, serve to explain the principles of the present disclosure.
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FIG. 1 schematically depicts a system for real time inspection of an object during additive manufacturing of the object according to the present disclosure; -
FIG. 2 illustrates operations performed in a method for real time inspection of an object during additive manufacturing of the object according to the present disclosure; -
FIG. 3 schematically depicts a system for real time inspection of a metal object during additive manufacturing of the metal object by directed energy deposition according to the present disclosure; -
FIG. 4 schematically depicts another system for real time inspection of a metal object during additive manufacturing of the metal object by directed energy deposition according to the present disclosure; -
FIG. 5 illustrates operations performed in a method for real time inspection of an object during additive manufacturing of the object according to the present disclosure. - Reference will now be made in detail to exemplary implementations of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In the following description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustration specific exemplary implementations in which the present disclosure may be practiced. These implementations are described in sufficient detail to enable those skilled in the art to practice the present disclosure and it is to be understood that other implementations may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, merely exemplary.
- Currently, additively manufactured objects must complete fabrication and be removed from the build chamber before they can be inspected. Continuing fabrication of an object with an internal defect, however, wastes time, material, and money. Removing the object from the build chamber prior to completion of fabrication for inspection, however, is difficult and time consuming. In some additive manufacturing methods, such as those that require an inert atmosphere or vacuum in the build chamber, removing the object prior to completion cannot be done without irreparable damage to the object. Furthermore, the build chamber can contain smoke, particles, and liquids that can impeded even visual inspection during additive manufacturing. Implementations of the present disclosure address the need for a system and method to nondestructively inspect an object in real time as it is being fabricated by additive manufacturing.
- The disclosed x-ray based system and method can nondestructively detect defects within an object in real time, as the object is being fabricated, by additive manufacturing. Inspection can be accomplished without needing to modify or otherwise disrupt the environment inside the build chamber, for example a vacuum, inert gas, or elevated temperature environment. Being x-ray based, the disclosed system and method is not limited by the type and size of the build chamber or the type of additive manufacturing technique being used, Moreover, the disclosed system and method is not affected by smoke, particles, or liquid that may be present in the build chamber. Real time detection of defects during additive manufacturing can save time, material, and money by stopping or correcting the process immediately upon detection of a defect instead of waiting until completion of the additive manufacturing process.
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FIG. 1 shows aninspection system 100 that can be used during additive manufacturing, according to the present disclosure.Inspection system 100 can include anx-ray tube 110, anaperture 120, anactuator 130, a linearx-ray detector array 140, acomputer 150, acontroller 154, and animage analyzer 156. -
X-ray tube 110 is positioned adjacent to and outside of abuild chamber 160.X-ray tube 110 can be, for example, an x-ray tube used for baggage screening in airports. The type ofx-ray tube 110 can depend on the objected being additively manufactured, its composition, and the type of additive manufacturing technique being used. For example,x-ray tube 110 can be glass or ceramic and have power ranging from about 100 to about 4000 watts and voltages ranging from about 30 to about 450 kV. Suitable x-ray tubes are manufactured by, for example, Phillips, Varian, and General Electric.X-ray tube 110 further includes a cooling system, for example, circulating water or closed cycle cooling to control the temperature of the x-ray tube. -
Aperture 120 is positioned betweenbuild chamber 160 andx-ray tube 110 to provide a collimated fan beam directed to an object being fabricated inside ofbuild chamber 160.Aperture 120 can be formed of any material that blocks x-rays, including but not limited to lead, steel, and tungsten.Aperture 120 is controlled bycontroller 154 to provide pulses of about 1 second to about 60 seconds directed at an object being fabricated inside ofbuild chamber 160.Aperture 120 can be, for example, a linear aperture formed of lead or steel. -
Actuator 130 is disposed within abuild chamber 160 and either directly or indirectly supports the object being fabricated.Actuator 130 can be a rotary actuator, such as a turntable, that rotates under the control ofcontroller 154, at a speed from about one revolution per second to about one revolution per 10 minutes. This allows the x-ray pulse to interact with the entire volume of the object being fabricated.Actuator 130 can be a motorized turntable with an optical encoder that provides accurate positioning so the x-ray image can correlate to the positon of the object being formed inside ofbuild chamber 160. Alternatively,actuator 130 can be a linear actuator that supports and moves the object being fabricated in a linear direction, for example, into and out of the page, as shown inFIG. 1 . The linear actuator can move under the control ofcontroller 154 at a speed from about 100 cm/sec to about 1 cm/minute to allow the x-ray pulse to interact with the entire volume of the object being fabricated. For example, the linear actuator can move the object being fabricated so that the entire volume of the object is scanned by the x-ray pulse. - Linear
x-ray detector array 140 is positioned outside ofbuild chamber 160 to detect the x-ray pulse after it passes through and interacts with an object being fabricated onactuator 130. Linearx-ray detector array 140 can be, for example, a one-dimensional x-ray detector consisting of at least one row of x-ray sensitive detectors. Data from linearx-ray detector array 140 is digitized and sent to acomputer 150 and analyzed byimage analyzer 156. By moving either the object being fabricated or the detector in a direction perpendicular to the length of linearx-ray detector array 140, a two dimensional image of the object can be created. As shown inFIG. 1 ,actuator 130 is a turntable that rotates the object being fabricated in a direction perpendicular to the length dimension of linearx-ray detector array 140. Linearx-ray detector array 140 can be, for example, a silicon (Si) or complementary metal-oxide-semiconductor (CMOS) based detector with scintillating materials on top. Scintillating materials can be, for example, CsI:Na, Gd2O2S, or CaWO4, to convert x-rays to visible light. In the case whereactuator 130 is a linear actuator, the linear actuator moves the object being fabricated in a direction into and out of the page, so that the entire volume of the object being fabricated is scanned by the linear x-ray pulse and the x-rays are detected by linearx-ray detector array 140 subsequent to the x-rays interacting with the object being fabricated. -
Inspection system 100 further includescomputer 150,controller 154, andimage analyzer 156.Computer 150 is operably coupled tox-ray tube 110,aperture 120,actuator 130, and linearx-ray detector array 140.Computer 150 includes processors and a memory system including one or more non-transitory computer readable media storing instructions that, when executed, synchronizes actions byx-ray tube 110,aperture 120,actuator 130, and linearx-ray detector array 140. In particular,computer 150, throughcontroller 154, synchronizes via processors and software, the rotation or linear movement ofactuator 130 with the exposure time of linearx-ray detector array 140 to maintain regular image geometry. This provides accurate positioning so the x-ray image can correlate with the position of the object being formed for pinpointing the defect location. This also allows accurate determination of when failure occurs in the additive manufacturing process.Controller 154further controls aperture 120 to provide an x-ray pulse having the desired pulse width and controls operation ofx-ray tube 110 to provide the desired energy. -
Image analyzer 156 can include, for example, software to create x-ray images from data received from linearx-ray detector array 140.Image analyzer 156 can further include software to identify defects in the x-ray images, for example, pattern recognition software that compares the x-ray images to defect-free x-ray images. For example, by comparing an x-ray image of the object being formed to an x-ray image of a defect free object, the pattern recognition software can identify anomalies or defects, such as unplanned voids or inconsistencies, in the x-ray image of the object being formed. One of ordinary skill in the art will understand that other components may be included ininspection system 100. For example other software/devices can be used to capture, manipulate, analyze, and display the x-ray images or to control other devices such as the hardware related to the additive manufacturing system including build material deposition and fusing. -
Build chamber 160, shown in cross section inFIG. 1 , is generally part of an additive manufacturing system. It can take on many forms depending on the type of additive manufacturing technique, but is generally an enclosure in which additive manufacturing occurs.Build chamber 160 can range from a simple glass or polymer enclosure to a complex enclosure in which temperature and/or pressure and/or atmospheric content is tightly controlled. An advantage of the disclosed system and method, is that it is independent of the type of build chamber because x-rays can penetrate most materials. -
FIG. 2 shows amethod 200 for nondestructive inspection of an object during fabrication by additive manufacturing according to the present disclosure.Method 200 is described herein with respect to a metal powder fedadditive manufacturing system 301 shown inFIG. 3 . Metal powder fed additive manufacturing systems are also known as laser cladding, directed energy deposition, and laser metal deposition systems. One of ordinary skill in art will understand that reference to metal powder fedsystem 301 is for descriptive purposes and that the disclosed system and method can be used in other types of additive manufacturing systems and is not limited to additive manufacturing of metal objects. - At 210 of
method 200 shown inFIG. 2 , deposition and fusing of material to form an object by additive manufacturing is paused.FIG. 3 shows a metal powder fedadditive manufacturing system 301 including abuild chamber 360, ametal powder feeder 380, and alaser beam 382. During additive manufacturing,metal powder feeder 380 deposits metal powder whilelaser beam 382 fuses the metal powder at the surface of anobject 399 being formed layer by layer. Metal powder feeder can include, for example, a nozzle mounted on a 4 or 5 axis arm. The type of laser can depend on the powdered metal being deposited. Because directed energy deposition systems often require an inert atmosphere, access to buildchamber 360 during fabrication by additive manufacturing is limited. - Real time, nondestructive inspection of
object 399 during additive manufacturing by metal powder fedsystem 301 can be accomplished by incorporating anx-ray tube 310, alinear aperture 320, anactuator 330, a linearx-ray detector array 340, acomputer 350, acontroller 354, andimage analyzer 156. Additive manufacturing systems, for example metal powder fedsystem 301 used for descriptive purposes herein, may already include a computer and controller that can be utilized. One of ordinary skill in the art will understand that software or hardware components may need to be added to the existing computer and controller of the additive manufacturing system to incorporate control ofx-ray tube 310,linear aperture 320,actuator 330, and/or linearx-ray detector array 340. Alternatively, another computer and controller, separate from the computer and controller of the additive manufacturing system, can be used. - At 210 of
method 200,metal powder feeder 380 pauses depositing metal powder and fusing bylaser beam 382, for example by turning off the laser that provideslaser beam 382 or redirectinglaser beam 382 away fromobject 399.Build chamber 360 does not need to be opened, the environment inside does not need to be changed, and object 399 does not need to be removed from the build chamber. This can minimize the amount of time the additive manufacturing process is paused. Pausing the additive manufacturing process can be simply stopping deposition and fusing of the build material for a brief period of time, for example, after formation of one layer and prior to formation of the next layer. When to pause the additive manufacturing process can be determined based on a number of factors including, but not limited to, the size and complexity of the object being fabricated, the number of inspections desired, and the type of additive manufacturing being used. For example, pausing at 210 can occur subsequent to fabrication of a complex portion ofobject 399 but prior to completion of fabrication ofobject 399. - At 220 of
method 200,actuator 330, such as a turntable, rotatesobject 399 in a direction perpendicular to a length dimension of linearx-ray detector array 340.Controller 354 can control the speed of rotation, as well as the start and stop of the rotation. Rotation ofactuator 330 can begin either before, during, or after x-rays interact withobject 399. The speed of rotation can depend on the size ofobject 399 and/or the x-ray pulse width and can range from about one revolution per second to about one revolution per 10 minutes. - Where
actuator 330 is a linear aperture,actuator 330 moves object 399 in a linear direction perpendicular and between linearx-ray detector array 340 andx-ray tube 310.Controller 354 can control the linear speed, as well as the start and stop of the linear motion. Movement of object being formed 399 byactuator 330 can begin either before, during, or after x-rays interact withobject 399. The speed of movement can depend on the size ofobject 399 and/or the x-ray pulse width and can range from about 100 cm/sec to about 1 cm/min. - At 230 of
method 200, an x-ray pulse is directed towardsobject 399. The x-ray pulse can occur at a time T1. Time T1 is subsequent to a time T0 and prior to a time TF, wherein time T0 is a start of additive manufacturing ofobject 399 and time TF is a completion of additive manufacturing ofobject 399 withinbuild chamber 360. Referring toFIG. 3 , x-rays are generated byx-ray tube 310.Linear aperture 320, under the control ofcontroller 354, provides a collimated fan shaped x-ray pulse that interacts withobject 399 as it is being rotated byactuator 330. The x-ray pulse can have a pulse duration of about 1 second to about 60 seconds and an energy of about 50 to about 250 keV. Current can range from about 1 to about 20 mA. The x-ray pulse duration allows x-rays to interact with the object being formed as the object is being rotated or moved linearly. Factors influencing pulse width include the size of the object being formed and the speed of rotation or linear movement. Typically, a larger object or slower rotation or movement will require a longer pulse width. Energy and current of the x-ray pulse are determined by the size and composition of the object being formed so that the x-rays can penetrate the object being formed and the build chamber before being detected.Linear aperture 320 provides a collimated fan beam having a narrow width. The collimated fan beam can further have a length, for example, long enough to inspectobject 399 at its largest dimensions when fabrication is completed. The path and pulse shape of the x-ray pulse are depicted inFIG. 3 as anx-ray pulse 311. - At 240 of
method 200,x-ray pulse 311 is detected by linearx-ray detector array 340. The speed ofactuator 330 movingobject 399 and the pulse width ofx-ray pulse 311 allow linearx-ray detector array 340 to detect the x-ray subsequent to interaction with an entire volume ofobject 399. For example, whereactuator 330 is a turntable, the turntable can rotateobject 399 one half turn to allowx-ray pulse 311 to interact withobject 399. As used herein, one half turn refers to object 399 rotating one half of one full rotation with respect to turntable orobject 399. Because x-rays will pass completely throughobject 399, the one half turn will allowx-ray pulse 311 to interact with the entire volume ofobject 399. In another example,actuator 330 can rotateobject 399 one full turn or more. The data collected by linearx-ray detector array 340 is sent tocomputer 350. At this point,controller 354 under the direction ofcomputer 350 can stop rotation ofactuator 330.Controller 354 controls actuator 330, whether a turntable or linear actuator, so thatobject 399 is at the same position after rotation or linear movement. In other words,controller 354 returns object 399 to the same position relative tometal powder feeder 380 andlaser beam 382 so that additive manufacturing can continue. - At 250 of
method 200, an x-ray image is created based on the x-rays detected by linearx-ray detector array 340. Using signals provided by linearx-ray detector array 340, an x-ray image representing a volume ofobject 399 can be created. The x-ray image can be, for example, a digital image created byimage analyzer 356. The x-ray image is analyzed at 260 ofmethod 200 byimage analyzer 356. For example,image analyzer 356 can use pattern recognition to compare the x-ray image ofobject 399 to control image, for example, an x-ray image of an object with no defects. Defects of about 1mm and larger can be detected. - If a defect is detected in
object 399, additive manufacturing can be stopped at 270. Stopping the additive manufacturing process at this point, prior to completion of fabrication, can save time, material, and cost. - If a defect is not detected in
object 399, the additive manufacturing can resume fabrication ofobject 399, as shown at 280 ofmethod 200. Referring toFIG. 3 , resuming additive manufacturing means thatactuator 330, for example, the turntable, under the direction ofcontroller 354, has stopped rotating andmetal powder feeder 380 begins to deposit metal powder whilelaser beam 382 fuses the metal powder at the surface ofobject 399. One of ordinary skill in the art will understand that fabrication can resume at any time after detection of the x-rays by linearx-ray detector array 340. In other words, additive manufacturing can resume before completion of the analysis of whether a defect exists. - At 290 of
method 200, fabrication ofobject 399 can continue to completion. If another inspection is desired, for example at a time T2, where T2 is subsequent to time T1 and prior to time TF, fabrication ofobject 399 can again be paused and can return to 210 ofmethod 200 as shown inFIG. 2 .Operations 210 thru 260 ofmethod 200 can then be repeated as desired or until fabrication is complete. In other words, between time T0 and TF and subsequent to T2, x-rays can be directed atobject 399 and x-ray images created as many times as desired. For example, subsequent to time T2 and prior to time TF, x-rays can be directed atobject 399 and x-ray images created at a time TN where time TN is an integer greater than 2. For small or non-complex shapes, only one inspection may be desired. For a large or complex shape and/or for an object formed of expensive build materials, the additive manufacturing process can be paused and the object inspected, for example, 10 times so that 10 x-ray images are formed at times T1 thru T10, respectively. Furthermore, when during the fabrication process each of the pauses occurs can also be determined as desired. For example, T1 (or TN) can be set to occur after fabrication of a particularly complex portion ofobject 399. Additionally, the timing of multiple pauses of the additive manufacturing process and inspection of the object does not have to be evenly spaced and can occur any time during fabrication. - As disclosed herein, some or all of
method 200 can be advantageously automated. For example, resuming or stopping the additive manufacturing process is accomplished without an operator by using, for example,computer 350,controller 354, andimage analyzer 356. Determining whether a defect exists using image processing and pattern recognition software can increase consistency of results. If desired, however, a trained technician can be used to perform the inspection and/or determination of whether a defect exists. -
FIGS. 4 and 5 show another inspection system and method that can be used for real time inspection during additive manufacturing, according to the present disclosure. Instead of rotating the object being formed, here the object being formed is stationary while one or both of the x-ray tube and the linear x-ray detector array is moved. As before, the inspection system and method are described with reference to metal powder fedsystem 401. Metal powder fedsystem 401 includes abuild chamber 460, afabrication stand 430, ametal powder feeder 480, and alaser beam 482.Metal powder feeder 480 can include, for example, a nozzle mounted on a 4 or 5 axis arm. The type of laser can depend on the powdered metal being deposited. Because directed energy deposition systems often require an inert atmosphere, access to buildchamber 460 during fabrication by additive manufacturing is limited. Anx-ray tube 410, anaperture 420, a linearx-ray detector array 440, acomputer 450, acontroller 454, and animage analyzer 456 can be incorporated into metal powder fedsystem 401. The path and pulse shape of the x-ray pulse provided byx-ray tube 410 depicted inFIG. 4 as anx-ray pulse 411. Additionally, anx-ray tube actuator 405 can be used to move one or both ofx-ray tube 410 andaperture 420. And, linear x-raydetector array aperture 406 can be used to move linearx-ray detector array 440. - In this system, fabrication stand 430 remains stationary and can support an object being fabricated 499. For example,
x-ray tube 410 and linearx-ray detector array 440 can both move linearly. Alternatively, one ofx-ray tube 410 and linearx-ray detector array 440 can rotate while the other moves in an arc to maintain a same relative distance between the two. Moving the x-ray tube and the linear x-ray detector array relative to the stationary fabrication stand can reduce disruption of the additive manufacturing process because the change in relative position of object being fabricated 499 to the positions ofmetal powder feeder 480 andlaser beam 482 can be minimized. - To facilitate linear, arc, or rotational motion of one or both of
x-ray tube 410 and linearx-ray detector array 440, actuators can be used. For example,x-ray tube 410 can be attached tox-ray tube actuator 405 that moves bothx-ray tube 410 andaperture 420 in a linear manner, for example into and out of the page depicted inFIG. 4 . Similarly, linearx-ray detector array 440 can be attached to linear x-raydetector array actuator 406 that also moves linearly, for example, into and out of the page ofFIG. 4 and in a synchronized manner with the movement ofx-ray tube 410 andaperture 420. Alternatively, linear x-raydetector array actuator 406 can rotate linearx-ray detector array 440 to match the movement ofx-ray tube actuator 405 that moves bothx-ray tube 410 andaperture 420 in arc. In another alternative, linear x-raydetector array actuator 406 can move linearx-ray detector array 440 in an arc to match the rotation ofx-ray tube actuator 405 that rotates bothx-ray tube 410 andaperture 420. By rotating one ofx-ray tube 410 and linearx-ray detector array 440 and moving the other in an arc, the distance between the two can be maintained. - With reference to
FIG. 4 , inspection during additive manufacturing can proceed as shown inFIG. 5 . Amethod 500 for real time inspection during additive manufacturing is similar to themethod 200 shown inFIG. 2 . In this case,controller 454 can control the speed, as well as the start and stop of the motion of bothx-ray tube actuator 405 and linear x-raydetector array actuator 406.Controller 454 also synchronizes their movement to scan the entire volume of object being fabricated 499. The speed of movement of one or both actuators can depend on the size of object being fabricated 499 and/or the x-ray pulse width and can range from about 100 cm/sec to about 1 cm/min. -
Method 500 is described herein with respect to a metal powder fedadditive manufacturing system 401 shown inFIG. 4 . One of ordinary skill in art will understand that reference to metal powder fedsystem 401 is for descriptive purposes and that the disclosed system and method can be used in other types of additive manufacturing systems and is not limited to additive manufacturing of metal objects. - At 510 of
method 500 shown inFIG. 5 , deposition and fusing of material to form an object by additive manufacturing is paused, for example, by stopping deposition of metal powder and turning off the laser that provideslaser beam 482 or redirectinglaser beam 482 away fromobject 499.Build chamber 460 does not need to be opened, the environment inside does not need to be changed, and object 499 does not need to be removed from the build chamber. This can minimize the amount of time the additive manufacturing process is paused. - At 520 of
method 500,x-ray tube actuator 405 and linear x-raydetector array actuator 406 can movex-ray tube 410 and linearx-ray detector array 440, respectively, in a linear manner, for example, into and out of the page ofFIG. 4 .Controller 454 synchronizes the linear motion so the object being fabricated 499 is scanned byx-ray pulse 411 and subsequently detected by linearx-ray detector array 440.X-ray tube actuator 405 also movesaperture 420 in a synchronized manner withx-ray tube 410 and linearx-ray detector array 440. - Alternatively, at 520 of
method 500,x-ray tube actuator 405 and linear x-raydetector array actuator 406 can rotate one ofx-ray tube 410 and linearx-ray detector array 440, and the other ofx-ray tube actuator 405 and linear x-raydetector array actuator 406 can move in an arc. This can maintain the distance betweenx-ray tube 410 and linearx-ray detector array 440.X-ray tube actuator 405 also movesaperture 420 in a synchronized manner withx-ray tube 410 and linearx-ray detector array 440.Controller 454 synchronizes the motion ofaperture 420,x-ray tube 410, and linearx-ray detector array 440 so the object being fabricated 499 is scanned byx-ray pulse 411 and subsequently detected by linearx-ray detector array 440. - At 530 of
method 500, an x-ray pulse is directed towardsobject 499 at the same time asx-ray tube actuator 405 movesx-ray tube 410 andaperture 420, and linear x-raydetector array actuator 406 moves linearx-ray detector array 440. In this manner,object 499 is scanned by the x-ray pulse as one or both of the x-ray tube and linear x-ray detector array are moved linearly, in an arc or rotated. The x-ray pulse can occur at a time T1. Time T1 is subsequent to a time T0 and prior to a time TF, wherein time T0 is a start of additive manufacturing ofobject 499 and time TF is a completion of additive manufacturing ofobject 499 withinbuild chamber 460. Referring toFIG. 4 , x-rays are generated byx-ray tube 410.Linear aperture 420, under the control ofcontroller 454, provides a collimated fan shaped x-ray pulse that interacts withobject 499. The x-ray pulse can have a pulse duration of about 1 second to about 60 seconds and an energy of about 50 to about 250 keV. Current can range from about 1 to about 20 mA. The x-ray pulse duration allows x-rays to interact with the object being formed as the x-ray tube and/or linear x-ray detector array is being moved linearly or in an arc. The collimated fan beam can further have a length, for example, long enough to inspectobject 499 at its largest dimensions when fabrication is completed. - At 540 of
method 500,x-ray pulse 411 is detected by linearx-ray detector array 540. The speed ofactuators object 499 and the pulse width ofx-ray pulse 411 allow linearx-ray detector array 440 to detect the x-rays subsequent to interaction with an entire volume ofobject 499. In other words, scanning of the entire volume ofobject 399 can be accomplished by controlling the pulse width and speed ofactuators x-ray detector array 440 is sent tocomputer 450. At this point,controller 454 under the direction ofcomputer 450 can stop motion ofactuators - At 550 of
method 500, an x-ray image is created based on the x-rays detected by linearx-ray detector array 440. Using signals provided by linearx-ray detector array 440, an x-ray image representing a volume ofobject 499 can be created. The x-ray image can be, for example, a digital image created byimage analyzer 456. The x-ray image is analyzed at 560 ofmethod 500 byimage analyzer 456. For example,image analyzer 456 can use pattern recognition to compare the x-ray image ofobject 499 to control image, for example, an x-ray image of an object with no defects. Defects of about 1 mm and larger can be detected. - If a defect is detected in
object 499, additive manufacturing can be stopped at 570. Stopping the additive manufacturing process at this point, prior to completion of fabrication, can save time, material, and cost. - If a defect is not detected in
object 499, the additive manufacturing can resume fabrication ofobject 499, as shown at 580 ofmethod 500. Referring toFIG. 4 , resuming additive manufacturing means thatmetal powder feeder 480 begins to deposit metal powder whilelaser beam 482 fuses the metal powder at the surface ofobject 499. One of ordinary skill in the art will understand that fabrication can resume at any time after detection of the x-rays by linearx-ray detector array 440. In other words, additive manufacturing can resume before completion of the analysis of whether a defect exists. - At 590 of
method 500, fabrication ofobject 499 can continue to completion. If another inspection is desired, for example at a time T2, where T2 is subsequent to time T1 and prior to time TF, fabrication ofobject 499 can again be paused and can return to 510 ofmethod 500 as shown inFIG. 5 .Operations 510 thru 560 ofmethod 500 can then be repeated as desired or until fabrication is complete. In other words, between time T0 and TF and subsequent to T2, x-rays can be directed atobject 499 and x-ray images created as many times as desired. For example, subsequent to time T2 and prior to time TF, x-rays can be directed atobject 499 and x-ray images created at a time TN where time TN is an integer greater than 2. For small or non-complex shapes, only one inspection may be desired. For a large or complex shape and/or for an object formed of expensive build materials, the additive manufacturing process can be paused and the object inspected, for example, 10 times so that 10 x-ray images are formed at times T1 thru T10, respectively. Furthermore, when during the fabrication process each of the pauses occurs can also be determined as desired. For example, T1 (or TN) can be set to occur after fabrication of a particularly complex portion ofobject 499. Additionally, the timing of multiple pauses of the additive manufacturing process and inspection of the object does not have to be evenly spaced and can occur any time during fabrication. - As disclosed herein, some or all of
method 500 can be advantageously automated. For example, resuming or stopping the additive manufacturing process is accomplished without an operator by using, for example,computer 450,controller 454, andimage analyzer 456. Determining whether a defect exists using image processing and pattern recognition software can increase consistency of results. If desired, however, a trained technician can be used to perform the inspection and/or determination of whether a defect exists. - While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it will be appreciated that while the process is described as a series of acts or events, the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and/or concurrently with other acts or events apart from those described herein. For example, steps of the methods have been described as first, second, third, etc. As used herein, these terms refer only to relative order with respect to each other, e.g., first occurs before second. Also, not all process stages may be required to implement a methodology in accordance with one or more aspects or implementations of the present teachings. It will be appreciated that structural components and/or processing stages can be added or existing structural components and/or processing stages can be removed or modified. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of” is used to mean one or more of the listed items can be selected. As used herein, the term “one or more of” with respect to a listing of items such as, for example, A and B, means A alone, B alone, or A and B. The term “at least one of” is used to mean one or more of the listed items can be selected. Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated implementation. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. Other implementations of the present teachings will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims.
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US20220402042A1 (en) * | 2019-11-15 | 2022-12-22 | Tritone Technologies Ltd. | Machine for additive manufacture incorporating molded layers |
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JP2020111044A (en) | 2020-07-27 |
US11474052B2 (en) | 2022-10-18 |
CN111426710A (en) | 2020-07-17 |
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JP7458767B2 (en) | 2024-04-01 |
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